Abstract

Structural and magnetic properties of the alloys have been investigated. It is found that for all of the investigated compositions, a phase transition occurs from the disordered phase to the ordered phase during cooling, while a reverse process takes place during heating. Moreover, magnetic fields also induce a phase transition from the phase to the phase near the transition temperature. The temperature- and magnetic-field-induced phase transitions give rise to a huge negative thermal expansion and thus a giant magnetic entropy change (up to for the alloy with ). The contribution of the magnetic field induced phase transition to the total magnetic entropy change is estimated to be around 20%–25%.